1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly, to an input receiver of a semiconductor device and a method of receiving an input data signal performed by the input receiver.
This application claims the benefit of Korean Patent Application No. 10-2005-0078909, filed on Aug. 26, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
2. Description of the Related Art
Semiconductor devices in a system transmit data signals to or receive data signals from one another. When receiving data signals, semiconductor devices need to determine whether the data signals are logic high or logic low. Therefore, semiconductor devices include an input receiver which receive data signals and determine whether the data signals are logic high or logic low.
Semiconductor devices in a system may transmit data signals to or receive data signals from one another in two different manners, i.e., a differential signaling method and a single-ended signaling method. An example of semiconductor devices operating in either the differential signaling method or the single-ended signaling method is disclosed in U.S. Pat. No. 6,590,429.
FIG. 1 is a diagram illustrating the waveforms of data signals transmitted between semiconductor devices using the differential signaling method. Referring to FIG. 1, in the differential signaling method, the semiconductor devices are connected to each other by two data transmission lines, and a data signal DATA and a complementary data signal /DATA are transmitted between the semiconductor devices via the respective data transmission lines. The differential signaling method can provide higher tolerance for common mode noise than the single-ended signaling method and can provide twice as wide an input data eye W1 as the single-ended signaling method. In the differential signaling method, however, two data signals, i.e., the data signal DATA and the complementary data signal /DATA, are transmitted together, thus increasing the number of pins required by semiconductor devices.
FIG. 2 is a diagram illustrating the waveform of a data signal transmitted between semiconductor devices using the single-ended signaling method. Referring to FIG. 2, in the single-ended signaling method, semiconductor devices are connected to each other by a single data transmission line, and a data signal DATA is transmitted between the semiconductor devices via the single data transmission line. The single-ended signaling method can reduce the number of pins required by semiconductor devices. However, the single-ended signaling method is more vulnerable to common mode noise than the differential signaling method and provides an input data eye W2 whose width is only half the width of an input data eye provided by the differential signaling method.
In the meantime, in order to reduce the manufacturing costs of a system and increase the performance of a system, input receivers of semiconductor devices in the system must be able to transmit as much data as possible using as few data transmission lines as possible and to provide as wide an input data eye as possible.